Nexus 7 data use

When looking through the task manager and opening android--data--com.firestudio--files, I find literally hundreds of icons labelled Panel A1 up to Panel F99, these are all film stills.
Then I get to A number of icons marked Shared Movies, these will not open.
Next comes Thumb nail User Online which are more film stills, then User Online which seem to be portrait photos some captioned "wire image", and finally YTHotNewly which are more film stills.
Where did they come from, and should I delete them as they must be using a lot of space.